This is a renewal of the training grant Training in Molecular Toxicology at UCLA that was first funded in 2008. The training grant has catalyzed the expansion and consolidation of molecular toxicological research and training at UCLA and has stimulated interactions and collaborations among the participating faculty and the pre- and postdoctoral trainees. During the current funding period, the number of training grant faculty members increased from nine to fourteen. The faculty has primary appointments in nine different departments at UCLA. Four of the new appointees are Assistant Professors, and represent potential future leaders of the program. Seven of the faculty members have M.D. degrees. These faculty provides a potential avenue for the recruitment of physician-scientists to postdoctoral (and perhaps also pre-doctoral) positions in the training grant. The training grant requests support for five years and for four pre-doctoral students in the Molecular Toxicology Interdepartment Doctoral Program (IDP) at UCLA, and two postdoctoral trainees in the laboratories of the training grant faculty. Pre-doctoral trainees wil usually be appointed for three years, and postdoctoral trainees will be appointed for up to two years. In general, only pre-doctoral trainees who have completed their first year (during which most do rotations) will be awarded positions on the training grant. This number of trainee positions requested is justified by the increase in the number of our faculty, their substantial NIEHS and non-NIEHS funding, the investigators' previous success in recruiting excellent pre-doctoral and postdoctoral trainees, and the excellent publication record of the trainees. The faculty has a common interest in the mechanisms whereby environmental toxins cause disease. There are four major foci of research interest: i) The role of pesticides in the etiology of Parkinson's disease, ii) genetic damage (including carcinogenesis) caused by environmental agents, (iii) the toxic effects of secondhand cigarette smoke and of fossil fuels and their combustion products, and iv) nanotoxicology. Other areas of research pursued by individual faculty include metal toxicity and the analysis of transcription networks in toxicity. The UCLA Vice Chancellor for Research very recently announced a Grand Challenge initiative. One of the six Challenges focuses on preventing diseases associated with energy, pesticides and environmental technologies. The training grant faculty and trainees are poised to make major contributions to this endeavor. The UCLA Academic Senate undertook an eight year review of the Molecular Toxicology IDP in 2010, and an External Advisory Committee reviewed the training grant in 2011. The Committees were clearly impressed with the IDP and the attainments of the training grant. UCLA has committed considerable resources to the Molecular Toxicology Program, and institutional support is very strong. Over the next five years the NIEHS training grant will further enhance and stimulate molecular toxicological research and training at UCLA, should encourage more students and postdoctoral fellows to pursue research in toxicology, and will signal the increasing importance of toxicology as a discipline at UCLA.